Connectors used for connections in electrical circuits in motor vehicles are required to have a high-degree of waterproof sealing performance as well as oil resistance. Oil-bleeding rubber materials are therefore used frequently as sealing rubber parts for these connectors, such as, e.g., packings and rubber plugs. Recently used as a molding material is an oil-bleeding silicone rubber comprising a silicone rubber having excellent heat, cold, and oil resistance and a silicone oil incorporated therein (see JP-A-62-252457; the term "JP-A" as used herein means an "unexamined published Japanese patent application").
Many techniques for bonding an addition-curing silicone rubber to an organic resin have hitherto been proposed. Examples thereof include a method in which a primer is applied to the surface of a molded resin and an uncured silicone rubber is applied to the primed surface and cured, and a method in which a self-bonding silicone rubber material is cured on a molded resin. With respect to this self-bonding silicone rubber composition, many proposals have been made especially on techniques concerning bonding ingredients therefor. Further, other techniques proposed so far include a method in which an organopolysiloxane containing directly silicon-bonded hydrogen atoms in an amount of at least 30 mol % is added to an organic resin and this organic resin is bonded to an addition-curing silicone rubber (JP-B-2-34311; the term "JP-B" as used herein means an "examined Japanese patent publication"); a method in which a silicone rubber is integrated with an organic resin by means of physical fitting (JP-B-63-45292); a method in which a silicone rubber is bonded to and integrated with an olefin resin onto which a compound having an aliphatic unsaturated group and a silicon-bonded hydrolyzable group has been grafted (JP-A-63-183843); and a method in which a thermoplastic resin containing a compound having an unsaturated group and a directly silicon-bonded hydrogen atom is bonded to and integrated with a silicone rubber, as proposed by the present inventors in the specification of a previous patent application.
However, the prior art techniques described above have drawbacks as follows. The method of using a primer for bonding necessitates the troublesome procedure of taking a molded resin out of the mold and priming the resin molding. The method of applying a self-bonding silicone rubber to a molded resin and curing the rubber has a serious drawback that when a mold or the like is used for the molding of the resin and the silicone rubber, the silicone rubber itself adheres to the mold. In addition, although use of the self-bonding silicone rubber poses no problem when it is cured after being applied to a resin molding, the addition-curing self-bonding silicone shows insufficient adhesion to some of many general-purpose resins, e.g., ABS, PPO, PPS, polycarbonates, acrylics, PE, PP, and Teflon, when it is used for producing integrally molded articles. Further, the method of adding a hydrogenpolysiloxane to an olefin resin, among the proposed techniques described above, has a drawback that the addition of the siloxane may modify properties of the resin itself, making it difficult to obtain the properties inherent in the resin. The method of using physical fitting for obtaining an integral article is disadvantageous in that the fitted parts may be separated from each other by a physical force. The method of using an olefin resin onto which a compound having an aliphatic unsaturated group and a silicon-bonded hydrolyzable group has been grafted has a drawback that use of a primer is necessary when an addition-curing silicone rubber is integrated with the olefin resin.
On the other hand, for eliminating these problems, there has been a desire for an integral waterproof connector made of a thermoplastic resin and, tenaciously bonded thereto, an oil-bleeding silicone rubber from which an oil bleeds out after molding.
In this respect, a technique for obtaining a tenaciously bonded integral molding from a thermoplastic resin having aliphatic unsaturated groups and a silicone rubber containing a specific bonding ingredient was proposed by the present inventors in JP-A-6-171021 and JP-A-6-171023. However, no proposals were made therein on adhesion to an oil-bleeding silicone rubber, because this bonding was technically difficult in those days.